Cigarettes having hollow fibers

ABSTRACT

Smoking articles, such as cigarettes and cigarette filters, methods of manufacturing smoking articles including hollow fibers, and methods of smoking are provided. In one exemplary embodiment, a smoking article contains hollow fibers, wherein the hollow fibers change properties of mainstream tobacco smoke drawn through the hollow fibers.

BACKGROUND

A wide variety of materials have been suggested in the art as filtersfor tobacco smoke. Such filter materials include cotton, paper,cellulose, and certain synthetic fibers. These filter materials areknown to remove particulates and condensable components from tobaccosmoke. They have little or no effect in removing certain gaseouscomponents, e.g., aldehydes, from tobacco smoke. See for examplecommonly assigned U.S. Pat. No. 6,209,547, which is hereby incorporatedherein in its entirety for all purposes.

SUMMARY

Smoking articles, such as cigarettes and cigarette filters, and methodsof manufacturing smoking articles are provided. In one exemplaryembodiment, a smoking article contains hollow fibers which affectmainstream tobacco smoke drawn through the smoking article.

In another exemplary embodiment, a cigarette, comprising: a tobacco rod;a filter joined to the tobacco rod, wherein the filter comprises abundle of hollow fibers, wherein the lumens of the hollow fibers arealigned axially in parallel to one another; and an additive material inextra-cellular spaces of the hollow fibers, wherein one end of at leastone of the hollow fibers is obstructed is provided.

In another exemplary embodiment, a cigarette filter, comprising: hollowfibers; an outer layer covering an outer region of the hollow fibers;and cellulose acetate, wherein the hollow fibers and the outer layer areembedded within the cellulose acetate is provided.

In another exemplary embodiment, a method of manufacturing a cigarettefilter, comprising: preparing hollow fibers with a smoke impermeablematerial covering one end of at least one of the hollow fibers; at leastpartially filling extra-cellular spaces within the hollow fibers with anadditive material; and placing the hollow fibers with the smokeimpermeable material and the additive material in a cigarette filter isprovided.

Also provided is a method of treating mainstream smoke, comprising:drawing tobacco smoke axially through hollow fibers, wherein themainstream tobacco smoke is drawn into an open upstream end into lumensof the hollow fibers and is drawn through permeable walls of the hollowfibers to a downstream end of a smoking article.

Also provided is a cigarette filter, comprising: a hollow fibermembrane, wherein the hollow fiber membrane comprises: hollow fibers;and a smoke impermeable material, wherein the smoke impermeable materialobstructs a downstream end of a lumen of the hollow fiber.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

FIG. 1 illustrates an exemplary embodiment cigarette including a hollowfiber membrane containing filter, and a path of fluid flow through thecigarette.

FIG. 2 illustrates a cross-section of a bundle of aligned hollow fiberswith open upstream ends and impermeable or semi-permeable materialfilling gaps between the hollow fibers.

FIG. 3 illustrates a cross-section of a bundle of aligned hollow fiberswith closed downstream ends and permeable material filling gaps betweenthe hollow fibers.

FIG. 4 illustrates another exemplary embodiment cigarette including ahollow fiber membrane containing filter, and a path of fluid flowthrough the cigarette.

FIG. 5 is an exemplary illustration of a cross-section of a hollowfiber.

FIG. 6 is photomicrograph of extra-cellular spaces of an exemplaryhollow fiber.

FIG. 7 illustrates an exemplary embodiment cigarette including a hollowfiber membrane and a sorbent in a filter, and a path of fluid flowthrough the cigarette.

DETAILED DESCRIPTION

Smoking articles are provided that include hollow fibers therein,wherein the hollow fibers are obstructed on one end to force a fluidthrough the walls of the hollow fibers.

As used herein, the term “feed” is used to indicate a material or fluidwhich is fed into the hollow fibers. Also as used herein, the term“retentate” is used to indicate the portion of the feed which does notpass through the walls of the hollow fibers and is trapped within or onan outer surface of the lumens of the hollow fibers. Additionally, theterm “filtrate” is used to indicate the portion of the feed which passesthrough the walls of the hollow fibers.

The term “obstruct” is intended to include blocking, partial blocking,filtering, or any other means of reducing flow through an area. Forexample, an impermeable or semi-permeable material can be used toobstruct the downstream end of the hollow fibers by blocking filtrate orfeed from passing through a downstream end of the hollow fibers, or bymerely increasing the resistance to flow for filtrate or feed passingthrough the downstream end of the hollow fibers.

An exemplary use of a cigarette 100 with hollow fibers is illustrated inFIG. 1, wherein the hollow fibers are utilized as hollow fibermembranes. As illustrated in FIG. 1, upon lighting a cigarette 100 at anupstream end 110 of the cigarette 100 and applying a drawing action tothe downstream end 120, a smoke feed 140 (a flow of mainstream tobaccosmoke) would travel in a downstream direction. The smoke feed 140 wouldpass from the upstream end 110 through a tobacco rod 50, then through afilter section 130, then through the downstream end 120 of the cigarette100.

Upon entry into the filter section 130, the smoke feed 140 is forcedinto lumens, or inner diameters, 15 of hollow fibers 10 within thefilter section 130. In FIG. 1, the lumens 15 are unobstructed on theupstream ends 25 of the hollow fibers 10, but obstructed on thedownstream ends 35. The smoke feed 140 passing into the filter isdirected into the upstream ends 25 of the lumens 10 by a first filtrateobstructing or smoke impermeable material 20 (hereinafter “smokeimpermeable material” generally), which obstructs smoke feed 140 flowbetween the outer circumference of the bundle of fibers 10 and the innerdiameter of the cigarette, as illustrated in FIG. 1.

Additionally, the first smoke impermeable material 20 can also beprovided between the individual fibers 10 in the bundle, as illustratedin FIG. 2, to obstruct fluid flow between the fibers 10 in the bundle.An exemplary cross-section illustration of the first smoke impermeablematerial 20 surrounding the hollow fibers 10 in the bundle, while notobstructing the upstream end 25 of the lumens 15, is illustrated in FIG.2.

Next, also as illustrated in FIG. 1, the smoke feed 140 is forced fromthe lumens 15 through the walls of the hollow fibers 10 by a secondsmoke impermeable material, which obstructs the downstream ends 35 oflumens 15 of the hollow fibers 10. FIG. 3 is an exemplary cross-sectionillustration of the second smoke impermeable material obstructing thedownstream ends 35 of the lumens 15 of the hollow fibers 10.

It is noted that as illustrated in FIG. 3, the downstream ends 35 of thehollow fibers 10 can include a filtrate permeable material 30 betweenthe hollow fibers 10, as well as between the outer circumference of thebundle of fibers 10 and the inner diameter of the cigarette filter 130,if desired. As provided herein, the filtrate permeable material 30 canbe any material that allows filtrate to pass through the filtratepermeable material 30 for ejection out of the downstream end 120 of thecigarette 100.

The filtrate permeable material 30 can be provided to hold the hollowfibers 10 in place in relation to one another, as well as in relation tothe filter 130. Alternatively, a ring, an adhesive, or other physicallycontaining material can be used, as long as it does not substantiallyobstruct filtrate flow through the filter 130. An exemplary embodimentof the filtrate permeable material 30 is a porous, filtrate permeablematerial, such as cellulose acetate.

By obstructing the downstream ends 35 of the hollow fibers 10, smoke 140is forced through the walls of the hollow fibers 10 because of thepressure exerted by the smoker on the downstream end 120. By forcingsmoke 140 through the hollow fibers 10, the walls of the hollow fibers10 can be used to filter smoke 140 therethrough. Thus, the walls of thehollow fibers 10 behave as a membrane in that the walls of the hollowfibers 10 allow the filtrate 150 from the smoke 140 to pass, while theretentate (not shown) is trapped within the lumens 15.

It is noted that in another exemplary embodiment, illustrated in FIG. 4,which is similar to FIG. 1, the filter 130 can be reversed. In otherwords, the first smoke impermeable material 20 can be formed to obstructan upstream end 25 of the lumens 15 so as to not allow smoke to enterthe lumens 15 on the upstream end 25 of the hollow fibers 10. It isnoted that the first smoke impermeable material 20 in FIG. 4 is formedin a similar fashion to the second smoke impermeable material 35illustrated in FIG. 3, wherein the first impermeable material is formedwithin the lumens 15 of the upstream end 25 of the hollow fibers.Additionally, similar to FIG. 3, a filtrate permeable material 30 canalso be provided between hollow fibers 10 for the same reasons asdiscussed above with respect to FIG. 3.

Additionally, as also illustrated in FIG. 4, a second smoke impermeablematerial 30 can be used to obstruct fluid flow between the outercircumference of the bundle of hollow fibers 10 and the inner diameterof the cigarette filter 130, as well as between the hollow fibers 10,similar to the first smoke impermeable material 20 of the embodimentillustrated in FIG. 1.

By providing the two smoke impermeable materials 20, 30, smoke feed 140can be routed between an outer circumference of the bundle of fibers 10and the inner diameter of the cigarette filter 130 at an upstream end25, through the walls of the hollow fibers 10 and out the downstream end35. By passing the smoke filtrate 150 through the walls of the hollowfibers 10, the hollow fibers 10 behave as a hollow fiber membrane inthat the smoke is separated into retentate and filtrate 150, wherein theretentate (not shown) can be trapped on the outer surfaces of the hollowfibers 10. After passing through the walls of the hollow fibers 10, thefiltrate 150 can then be passed through the downstream end 35 of thehollow fibers 10.

The hollow fibers 10 used herein are preferably embodied, as illustratedin FIG. 5, by porous or semi-porous fibers 10 with lumens 15 (hollowinner diameters) with a wall 18 thickness with at least some porosity19. The hollow fibers can be made of any porous or semi-porous material,wherein the porosity levels can be tailored to provide predeterminedlevels of permeability and also to contain extra-cellular spacestherein. For example, hollow fibers can be made of polymers, whereincellulose, modified cellulose, cellulose acetate, polypropylene,polysulfone, acrylic compounds and silicone rubber are preferableembodiments. Further discussion of hollow fiber materials can be foundin U.S. Pat. No. 3,708,071, which is hereby incorporated herein in itsentirety by reference for all purposes.

It is noted that the material used for the hollow fibers 10 can bechosen to have a predetermined pore size by determining the materialsused for the walls. For example, if the hollow fibers 10 are made oflarger pore materials, larger constituent filtrates are allowed to passthrough. Thus, the material used for the hollow fibers 10 can be chosento selectively restrain passage to only certain ranges of filtrates, ifdesired.

In a preferred smoking article, hollow fibers 10 are oriented in adirection in which smoke will travel through the smoking article. Byproviding such alignment, smoke can travel through lumens of the hollowfibers in a direction approximately parallel to the suction or vacuumforce applied at the downstream end of the smoking article drawing smokefrom the upstream or lit end.

Additionally, the hollow fibers 10 are approximately parallel to the oneanother in order to allow smoke feed 140 to evenly penetrate the hollowfibers 10, pass through the walls of the hollow fibers evenly, and forfitting bundles of hollow fibers into the axis of a cigarette. Forexample, as illustrated in FIG. 1, the axes of the lumens 15 arepreferably aligned parallel to one another (as well as parallel to theaxis of the cigarette), wherein such alignment allows smoke feed 140 toflow through the multiple lumens directly (i.e., without detour orindirect routing) while smoking of the cigarette.

These hollow fibers 10 can be used within any smoking article, like atraditional or non-traditional cigarette, e.g., in a cigarette filter.Preferred embodiments provide hollow fibers for use in smoking articles,such as cigarettes and non-traditional cigarettes. Non-traditionalcigarettes include, by way of example, cigarettes for electrical smokingsystems as described in commonly-assigned U.S. Pat. Nos. 6,026,820;5,988,176; 5,915,387; 5,692,526; 5,692,525; 5,666,976; and 5,499,636,the disclosures of which are hereby incorporated by reference herein intheir entireties.

Hollow fibers are preferably sized to a length less than the length of afilter so that the entire length of the fiber can fit within the area ofthe filter as the hollow fibers are aligned in the direction of smokeflow. Also, the diameters of the lumens of the hollow fibers (incombination with the material used to make the hollow fibers and thedensity of any bundle of hollow fibers) control the amount of flowpossible, as well as the force required to pull the tobacco smokethrough the hollow fibers (hereinafter, resistance to draw (RTD)).

In addition to using hollow fibers as hollow fiber membranes to filtermaterials, such as smoke, therethrough, the hollow fibers can also beused to provide additives. For example, as illustrated in FIG. 6, hollowfibers can include porosities (i.e., extra-cellular spaces) in the wallsof the hollow fibers. Within these extra-cellular spaces, additivematerials can be stored, wherein the additive materials can be byfluids, such as smoke, passing through the walls of the hollow fibersand thus through the extra-cellular spaces.

The outer diameter and wall thickness of the hollow fibers arepreferably sized to optimize the hollow fibers' ability to hold additivematerials and to control filtrate flow through the walls and retentatetrapping on the walls . It is noted that additive materials tend not tobe absorbed in the lumen of the hollow fibers due to capillary forces,thus the holding of additive materials is primarily carried out by theextra-cellular spaces within the walls. As the outer diameter of thehollow fibers increases, and/or the number of hollow fibers providedincreases, the amount of the porous spaces within walls of a hollowfiber (i.e., extra-cellular spaces, such as crack or crevices in wallsof hollow fibers) would tend to increase. By increasing the amount ofextra-cellular spaces, more additive materials can be absorbed. On theother hand, narrower lumens, and/or fewer hollow fibers can cause thehollow fibers to hold less additive materials due to their lesser totalouter surface wall areas.

Preferred embodiment hollow fibers 10 are used to releasably holdadditive materials within the extra-cellular spaces of the hollow fibers10. Thus, because of the releasable hold, additive materials in thehollow fibers 10 can be sufficiently contained to substantially avoid orminimize unwanted migration of the additive materials, such as, forexample, during storage of the smoking articles with the additivematerials therein.

In order to provide additive materials in hollow fibers, the additivematerials are provided for absorption or adsorption within theextra-cellular spaces of the hollow fibers 10. For example, additivematerials can be provided by soaking the hollow fibers 10 in a bath ofadditive materials, wherein the additive material can be absorbed intothe extra-cellular spaces.

Therefore, in an average sized cigarette (e.g., a cigarette with alength between 65-100 mm, a diameter of 6-9 mm and a filter length of15-30 mm), the hollow fibers can have a lumen (i.e., inner) diameter ofapproximately 50 microns to approximately 1500 microns (e.g., 50-100,100-150, 150-250, 350-500, 500-1000, or 1000-1500 microns), preferablyapproximately 90 microns to approximately 450 microns. Additionally, thehollow fibers can have a highly porous wall with a thickness ofapproximately 10 microns to 100 microns, preferably approximately 10 toapproximately 50 microns, and an outer diameter of approximately 100microns to approximately 2100 microns, preferably 100 to approximately500 microns.

For example, an exemplary embodiment cigarette can be designed toinclude a bundle of 10 to 15 hollow fibers, wherein each hollow fiberhas a lumen diameter of approximately 200 microns, a wall thickness ofapproximately 50 microns with an outer diameter of approximately 350microns.

Hollow fibers can be made by spinning or other fiber making techniques.For example, methods of making hollow fibers have been described in U.S.Pat. Nos. 2,999,296 and 4,234,431, which are hereby incorporated hereinin their entireties by reference.

In order to use the hollow fibers 10 in a smoking article, the hollowfibers 10 are cut or otherwise made to a specific length. The hollowfibers 10 can preferably be used in a circumferentially spaced relationin a filter section of a smoking article or can be gathered into abundle prior to insertion into a final product. If the hollow fibers arebundled, the hollow fibers 10 can be held together using a permeable,semi-permeable or impermeable material, as mentioned above, anenclosure, such as a ring, or an adhesive, such as triacetin, epoxy, andsilicone rubber.

Additionally, because of the releasable hold, the additive materials arepreferably mobile enough within the extra-cellular spaces of the hollowfibers to be released therefrom upon demand. For example, the additivematerial can preferably be released from the hollow fibers uponapplication of a vacuum force or drawing action as mentioned above.

Hollow fibers 10 can also be incorporated into a cigarette filter toprovide a means for controlling a resistance to draw (RTD) in acigarette. In a preferred embodiment, a cigarette filter would includehollow fibers 10 therein. By providing hollow fibers in a cigarette, acigarette can be provided with as little or as much resistance to drawas desired.

Additionally, hollow fibers 10 can be used to supplement or replacemulti-section filter assemblies, which are often more difficult tomanufacture than hollow fibers 10. Thus, hollow fibers 10 in cigarettefilters could be used to simplify the manufacturing process while stillproviding tailored levels of RTD.

2. Potting Materials

As mentioned above, first and second filtrate obstructing or smokeimpermeable materials can be used to obstruct smoke flow through asmoking article as illustrated in FIGS. 1 and 4. These filtrateobstructing or smoke impermeable materials along with semi-permeable orpermeable material used to hold the hollow fibers can be generallyreferred to as “potting material.”

As used herein, “potting material” is intended to include materials thatcan be used to hold hollow fibers in place, as well as materials thatcan direct feed, filtrate, and retentate flow in, around and throughlumens of the hollow fibers. As such, the potting material can be madeof any non-toxic, permeable, semi-permeable or impermeable material thatcan hold the hollow fibers in a fixed positional relationship with oneanother (i.e., in parallel to one another). Further discussion of hollowfiber membranes in potting material can be found in U.S. Pat. Nos.3,228,887, 3,528,553 and 6,685,832, which are hereby incorporated hereinin their entireties by reference.

Preferably, the potting material is a polymer or a composite, whereinthe material can be selected depending upon the degree of permeabilitydesired. For potting material used to obstruct airflow through an end ofa hollow fiber, a filtrate impermeable or semi-permeable pottingmaterial may be desired. For example, epoxy is a filtrate impermeablepotting material. On the other hand, for potting material used to holdthe fibers in place, wherein filtrate obstruction is not desired, apermeable potting material may be desired. For example, celluloseacetate is a permeable potting material.

The potting material can be formed on any portion of the hollow fibers10. For example, the potting material can be formed on a portion or theentirety of the length, the circumference of the fibers, and/or on endsof the hollow fibers. However, if the potting material is chosen toobstruct airflow, the potting material is preferably formed on less thanthe entire surface of the hollow fibers, as to allow for at least somefiltrate to pass through walls 18 of the hollow fibers 10.

Additionally, less than full coverage of the walls 18 of the hollowfibers 10 can be desired to not completely enclose and possibly isolatethe extra-cellular spaces and additive materials that can be containedtherein. As such, coverage by the potting material on the hollow fibers10 is preferably less than 90% of the wall surface of the hollow fibers10, and even more preferably, less than 60% of the wall surface of thehollow fibers 10 (e.g., 100-90%, 90-80%, 80-70%, 70-60%, 60-50%, 50-40%,40-30%, 30-20%, 20-10% or 10-0%).

The potting material can be formed on the hollow fibers in any mannerthat provides the airflow controlling properties desired by theembodiment. For example, methods of forming potting material on hollowfibers have been discussed in U.S. Pat. Nos. 6,702,561, 6,663,745,6,623,637 and 5,480,553, which are incorporated herein in theirentireties by reference.

As mentioned above, the potting material can be made of any materialthat can obstruct smoke passage. As such, the potting material can bemade of an impermeable, semi-permeable or permeable material. If thepotting material is a semi-permeable or permeable material, then thepotting material can be used as permeable barrier and can increase theresistance to airflow therethrough.

Therefore, a smoking article can be provided with hollow fibers in aconformation such that the structure and orientation for the hollowfibers 10 allows for at least some of the extra-cellular spaces ofhollow fibers 10 to be accessible to hollow fibers. Additionally, asprovided herein, the smoke flow can still be at least partially directedthrough the lumens 15 and the walls 18 of the hollow fibers 10, whereinadditive materials in the extra-cellular spaces can interact with theairflow as it passes through the walls 18 of the hollow fibers 10.

3. Outer Layer

The hollow fibers 10 can also include an outer layer covering orencapsulating the hollow fibers 10 (with additive material therein, ifdesired). Preferably, the outer layer is a solid wall or film, whereinthe solid wall or film can be used to temporarily seal or encapsulatethe hollow fibers 10 (and anything encapsulated within the hollow fibers10) away from the surrounding environment.

Preferably, the outer layer is applied around the outer surfaces of thehollow fibers 10 such that additive materials added to the hollow fibers10 can be sealed within the hollow fibers 10, and/or within theirextra-cellular spaces. Further, the outer layer is preferably easilyfrangible and can be ruptured to allow additive materials to be releasedfrom the hollow fibers 10.

The outer layer can be any frangible material, such as a polymer, whichis capable of both sealing the hollow fibers, as well as breaking,rupturing or perforating on demand. Preferably, the outer layer is madeof sugar or pectin, which can also be provided to flavor filtrate, suchas smoke filtrate, contacting the outer layer if desired. The outerlayer is preferably used to immobilize additive materials within thehollow fibers 10, and thus preferably reduces dissipation of theadditive material until the outer layer is broken, ruptured orperforated.

Preferably, the outer layer is a frangible thin film. By providing afrangible thin film, a difference in fluid pressure on either side ofthe outer layer and the hollow fiber walls (i.e., drawing on a cigarettewith hollow fibers and the outer layer therein) can be sufficient tocause the outer layer to break to release the additive materialstherefrom.

For example, in a cigarette, an outer layer can be designed to breakwhen smoke is drawn through the walls of the hollow fibers, wherein thevacuum pressure of drawing the smoke can cause the outer layer to break.In other words, when a smoker can puff on a cigarette causing the outerlayer to be broken by the smoke being drawn through the walls of thehollow fibers and additive materials can be released into the smoke asit passed through the walls of the hollow fibers.

The outer layer can be formed by any method capable of applying a filmthat is sufficiently thin to allow vacuum pressure to rupture the film.Preferably, the outer layer is applied by spraying a film formingmaterial onto the outer surfaces of hollow fibers and allowing for thefilm forming material to solidify into a film to provide an outer layer.

4. Smoking Articles

In a preferred embodiment, the hollow fibers 10 are used in smokingarticles, along with sorbents, such as microporous materials, to filteror remove gas phase constituents from cigarette smoke. Sorbents (i.e.,microporous sorbents) such as an activated carbon and/or a zeolitesorbent can be used.

While any suitable material can be used as a sorbent, a preferredembodiment includes activated carbon. However, sorbents can hinder acigarette designer's ability to add materials, such as volatile flavorcomponents like menthol, as the sorbents can adsorb and/or absorbmigrating volatile compounds during the time between cigarettemanufacture and its being smoked.

Two problems occur when additive materials, such as volatile flavorcomponents, are included in smoking articles with sorbents: first, theadditive materials can migrate throughout the smoking article; andsecond, the additive materials can be adsorbed or absorbed by thesorbents. These problems have previously been addressed by usingcentrally located flavor elements in commonly assigned U.S. patentapplication Ser. No. 2003/0224918, as well as filters for a smokingarticle containing a flavored hollow fiber in U.S. Pat. No. 4,971,078,both of which are incorporated herein in their entirety by reference.

When additive materials are sorbed by sorbents, not only can additivematerials be lost, but also the additive materials can also occupyactive sites in the sorbent. If the additive materials occupy activesites in the sorbent, the ability of the sorbent to remove targetedgases or constituents from smoke can be compromised. However, hollowfibers 10 can be used to overcome this problem by containing andisolating the additive materials from the sorbent prior to smoking, andtherefore avoiding interaction between the additive materials and thesorbent during storage.

In a cigarette filter, in addition to the hollow fibers 10 and thesorbent, a molecular sieve material can also be present. Preferably, themolecular sieve material can be present in monolithic or particle formsized at about 0.1 mm to 1 mm, and more preferably 0.3 mm to about 0.9mm (e.g., 0.3 mm to 0.4 mm, 0.4 mm to 0.5 mm, 0.5 mm to 0.6 mm, 0.7 mmto 0.8 mm or 0.8 mm to 0.9 mm) to facilitate processing into cigarettefilters so as to achieve a desirable filter pressure drop or RTD(resistance to draw).

Various filter constructions known in the art can be used, in whichhollow fibers 10 can be incorporated. Exemplary filter structures thatcan be used include, but are not limited to, a mono filter, a dualfilter, a triple filter, a single or multi cavity filter, a recessedfilter, a free-flow filter, combinations thereof and the like. Filterelements are typically constructed from cellulose acetate tow orcellulose paper materials.

The length and pressure drop of the segments in a dual filter can beadjusted to provide optimal sorption, while maintaining acceptable drawresistance. Triple filters can include mouth and smoking material ortobacco side segments, and a middle segment comprising paper. Cavityfilters include two spaced-apart filter plugs. The filters can also beventilated and/or comprise additional sorbents (such as activatedcarbon), catalysts or other additives suitable for use in a cigarettefilter.

Additionally, in an exemplary embodiment, a cigarette 100 with a bundleof hollow fibers 10 in the filter 130 can also include a sorbent 60. Forexample, as illustrated in FIG. 7, a cigarette 100 can be provided witha filter 130 which includes hollow fibers 10 with an additive material,such as a flavorant, therein and a sorbent upstream 60 (away from thesmoker and toward the tobacco portion 50). As sorbents are typicallyeffective for adsorbing or absorbing material added, such as aflavorant, placing the sorbent 60 upstream from the flavorant in thehollow fibers 10 can reduce the level of absorption or adsorption of theflavorant by the sorbent 60.

Preferably, the hollow fibers 10 can be located in a portion of thefilter 130 downstream from the sorbent 60 with a section of filtermaterial 70, such as cellulose acetate, between the two, as illustratedin FIG. 7. Preferably, the hollow fibers 10 and the sorbent 60, ifprovided, would be placed in cavities within a filter assembly 40.However, both the hollow fibers 10 and the sorbent 60, if provided, canbe placed anywhere within a filter 130 of a smoking article.

While a preferred filter includes a sorbent and hollow fibers 10, thehollow fibers 10 can also be used in smoking articles without a sorbentin the filter, as illustrated in FIGS. 1 and 4. Regardless of the typeof article in which the hollow fibers 10 is incorporated, the hollowfibers 10 can be used to provide effective containment and delivery ofmaterials, such as volatile flavors or other smoking related chemicals.

5. Additives

Hollow fibers can desirably be used to encapsulate additives in asmoking article, as mentioned above, wherein additives can beencapsulated within extra-cellular spaces of the hollow fibers. By suchencapsulation, additives can both be protected from loss and can bemixed with entrainment air as air passes through the walls of the hollowfibers.

In order to immobilize or encapsulate additives within hollow fibers 10,hollow fibers 10 are preferably soaked in additives. Soaking allows theadditives to be absorbed into extra-cellular spaces 35 of hollow fibers10, where the additives can remain due to capillary forces, thuspreventing dissipation of the additives.

The hollow fibers 10 can preferably be placed in a smoking article, morepreferably a cigarette filter, where the hollow fibers 10 are aligned ina cigarette for airflow. For example, the long axes of the hollow fibers10 can be aligned with the long axis of the cigarette for airflowpurposes. Also, a downstream potting material 30 can be used to obstructfluid flow through the downstream end of the hollow fibers 10.

Additionally, an outer layer can be formed on the hollow fibers 10 inorder to prevent dissipation and to further encapsulate additivematerials in extra-cellular spaces of the hollow fibers, as mentionedabove.

The additives can be flavors, which can be selected from any number ofknown artificial and natural materials, such as, for example,peppermint, spearmint, wintergreen, menthol, cinnamon, chocolate,coffee, tobacco, vanillin, licorice, clove, anise, sandalwood, geranium,rose oil, vanilla, lemon oil, cassia, spearmint, fennel, ginger,ethylacetate, isoamylacetate, propylisobutyrate, isobutylbutyrate,ethylbutyrate, ethylvalerate, benzylformate, limonene, cymene, pinene,linalool, geraniol, citronellol, citral, peppermint oil, orange oil,coriander oil, borneol, fruit extract and the like. Illustrative of suchtobacco flavorants are those described in U.S. Pat. Nos. 3,580,259;3,625,224; 3,722,516; 3,750,674; 3,879,425; 3,881,025; 3,884,247;3,890,981; 3,903,900; 3,914,451; 3,915,175; 3,920,027; 3,924,644;3,966,989; 4,318,417; and the like, which are incorporated herein byreference in their entirety.

The additives can also be chemicals, wherein the chemicals can be usedto attract or repel aerosols, or react with smoke constituents to removeor chemically extract smoke constituents.

For example, chemicals which can be used to attract or repel aerosolsinclude surfactants containing distinct hydrophobic (apolar) andhydrophilic (polar) regions. For example, polar surfactants can be usedto attract or repel selected tobacco smoke constituents like polartobacco constituents due to intrinsic attractive polarity properties.For example, by attracting tobacco smoke constituents, these tobaccosmoke constituents can be trapped and held within the hollow fiberschemically (in addition to mechanically being selectively separated bypore size of the walls of the hollow fibers, as mentioned above).

As mentioned above, chemicals or chemical systems can also be used toreact with smoke constituents to remove smoke constituents. For example,chemical systems such as aminopropylsilyl (APS), aminoethylaminopropylsilyl (AEAPS) and aminoethylaminoethyl aminopropylsilyl(AEAEAPS) can be used. See commonly assigned U.S. Pat. Nos. 6,595,218and 6,209,547, both of which are hereby incorporated herein by referencein their entirety.

As mentioned above, chemicals can also be used to react with smokeconstituents to extract smoke constituents. The term “chemicalextractive smoking” is intended to mean providing predetermined tobaccosmoke constituents to a smoker without any combustion of tobacco (i.e.,smokeless smoking).

Chemical extractive smoking provides a chemical or reagent, such aswater or alcohol, for interaction with tobacco in a tobacco product. Byallowing the chemical or reagent to interact with tobacco, a tobaccoenriched chemical or reagent can be formed, which in turn can be inhaledas a vapor or aerosol. For example, the chemical or reagent can besolvents, such as water or alcohol, such as ethyl alcohol. Preferably,the chemical extractive smoking occurs at lower than combustiontemperatures; however heat can be utilized to promote vaporization (orvolatilization) of the tobacco enriched chemical or reagent.

However, it is noted that heat can be used to increase the vapor and thesolubility of the tobacco constituents for “smoking.” By using heat, thetobacco enriched chemical or reagent can be heat vaporized and themobilization of the tobacco properties within the vapor can potentiallybe increased.

As an exemplary embodiment of a chemical extractive smoking article, acigarette can be made with hollow fibers including immobilized chemicalstherein. When “smoked,” the drawing action on one side of the hollowfibers 10 releases chemicals into the tobacco, whereupon the chemicalscause extractive release of a tobacco aerosol.

While the invention has been described in detail with reference tospecific embodiments thereof, it will be apparent to those skilled inthe art that various changes and modifications can be made, andequivalents employed, without departing from the scope of the appendedclaims.

1. A cigarette, comprising: a tobacco rod; a filter operative with thetobacco rod, wherein the filter comprises a bundle of hollow fibers,wherein the lumens of the hollow fibers are aligned axially in parallelto one another; and an additive material in extra-cellular spaces of thehollow fibers, wherein one end of at least one of the hollow fibers isobstructed.
 2. The cigarette of claim 1, wherein the filter furthercomprises a plug of fibrous filter material, wherein the plug is locatedupstream and/or downstream from the hollow fibers in the filter.
 3. Thecigarette of claim 1, wherein the hollow fibers are located in a cavityof the filter.
 4. The cigarette of claim 1, wherein the obstructed endof the at least one of the hollow fibers comprises a first smokeimpermeable material located within the lumen of the at least one of thehollow fibers, wherein the impermeable material obstructs airflowthrough the obstructed end of the at least one of the hollow fibers. 5.The cigarette of claim 4, wherein the first smoke impermeable materialcomprises a polymer or a composite.
 6. The cigarette of claim 1, furthercomprising a second smoke impermeable material surrounding an upstreamor a downstream end of the bundle of hollow fibers, wherein the secondsmoke impermeable material obstructs airflow around the bundle of hollowfibers and directs airflow into lumens of the bundle of hollow fibers.7. The cigarette of claim 6, wherein the first smoke impermeablematerial comprises a polymer or a composite.
 8. The cigarette of claim1, further comprising an outer layer on the hollow fibers, wherein theouter layer and the hollow fibers comprise different materials.
 9. Thecigarette of claim 8, wherein the outer layer comprises sugar or pectin.10. The cigarette of claim 1, wherein the hollow fibers comprise apolymeric material.
 11. The cigarette of claim 1, wherein the hollowfibers comprise cellulose, modified cellulose, cellulose acetate,polypropylene, polysulfone, acrylic compounds, silicone rubber, ormixtures or combinations thereof.
 12. The cigarette of claim 1, whereinthe additive material comprises a flavorant, a reagent which chemicallyreacts with and selectively separates a gaseous component of a smokestream, a surfactant, a solvent, or mixtures or combinations thereof.13. The cigarette of claim 12, wherein the additive material comprisesmenthol.
 14. The cigarette of claim 1, wherein the hollow fiberscomprise a bundle of fibers, and wherein the cigarette further comprisesa ring, wherein the ring surrounds the bundle of fibers.
 15. Thecigarette of claim 1, wherein the hollow fibers comprises a bundle offibers, and wherein the cigarette further comprises an adhesive, whereinthe adhesive bonds walls of the bundle of fibers to other walls of thebundle of fibers.
 16. The cigarette of claim 1, wherein each of thehollow fibers has a lumen diameter of approximately 50 microns toapproximately 1500 microns.
 17. The cigarette of claim 1, wherein eachof the hollow fibers has a lumen an inner diameter of approximately 90microns to approximately 450 microns.
 18. The cigarette of claim 1,wherein the filter further comprises a sorbent.
 19. The cigarette ofclaim 18, wherein the sorbent is located upstream in the filter from thehollow fibers.
 20. The cigarette of claim 1, wherein the lumens of thehollow fibers are aligned with one another in a direction in which smokewill travel through the cigarette.
 21. A cigarette filter, comprising:hollow fibers; an outer layer covering an outer region of the hollowfibers; and cellulose acetate, wherein the hollow fibers and the outerlayer are embedded within the cellulose acetate.
 22. The cigarettefilter of claim 21, further comprising an additive material inextra-cellular spaces in the hollow fibers.
 23. The cigarette filter ofclaim 22, wherein the additive material comprises a flavorant, a reagentwhich chemically reacts with and selectively separates a gaseouscomponent of a smoke stream, a surfactant, a solvent, or mixtures orcombinations thereof.
 24. The cigarette filter of claim 22, furthercomprising a first smoke impermeable material located between outersurfaces of the hollow fibers and the inner diameter of the cigarettefilter on one end of at least one of the hollow fibers, and a secondsmoke impermeable material located on end portions of lumens of thehollow fibers at the other end of the hollow fibers.
 25. The cigarettefilter of claim 22, wherein the outer layer comprises sugar or pectin.26. A method of manufacturing a cigarette filter, comprising: preparinghollow fibers with a smoke impermeable material covering one end of atleast one of the hollow fibers; at least partially fillingextra-cellular spaces within the hollow fibers with an additivematerial; and placing the hollow fibers with the smoke impermeablematerial and the additive material in a cigarette filter.
 27. The methodof claim 26, wherein the at least partially filling the extra-cellularspaces within the hollow fibers with the additive material comprisessoaking the hollow fibers in the additive material for a time effectiveto at least partially fill the extra-cellular spaces with the additivematerial.
 28. The method of claim 26, further comprising forming anouter layer on an outer surface of the hollow fibers before placing thehollow fibers in the cigarette filter.
 29. The method of claim 28,wherein the forming of the outer layer comprises spraying a layer ofpectin or sugar on the outer surface of the hollow fibers.
 30. A methodof treating mainstream smoke, comprising: drawing tobacco smoke axiallythrough hollow fibers, wherein the mainstream tobacco smoke is drawninto an open upstream end into lumens of the hollow fibers and is drawnthrough permeable walls of the hollow fibers to a downstream end of asmoking article.
 31. A cigarette filter comprising a hollow fibermembrane, wherein the hollow fiber membrane comprises: hollow fibers;and a smoke impermeable material, wherein the smoke impermeable materialobstructs a downstream end of a lumen of the hollow fiber.
 32. Thecigarette filter of claim 31, wherein the hollow fiber membranecomprises more than one hollow fiber bundled and aligned in a directionparallel to one another and parallel to an axial direction of thecigarette filter, and/or wherein the hollow fiber comprises a porous,permeable material.
 33. The cigarette filter of claim 31, furthercomprising an additive material in extra-cellular spaces of the hollowfibers.
 34. The cigarette filter of claim 33, wherein the additivematerial comprises a flavorant, a reagent which chemically reacts withand selectively separates a gaseous component of a smoke stream, asurfactant, a solvent, or mixtures thereof.